When Thomas Edison invented the phonograph, it became possible for music to evolve from a strictly live experience to an on-demand experience. Music producers are responsible for the recording of live or arranged music.
The producer is responsible for everything from the type of room in which the music is to be recorded to the types of microphones used. Overall, the producer is responsible for making sure that the music sounds good.
In this case, the music is being compiled, recorded and arranged by the producer. Because computers have become the standard medium for recording, it is very easy for a producer to combine different parts of a song that are recorded separately.
Rudy Van Gelder is one of the most famous examples of live recording producers. He specialized in jazz, and has produced such artists as Miles Davis, Thelonious Monk, and John Coltrane.
Quincy Jones, Timbaland, RJD2 and MF Doom are examples of arranged recording producers.